Video image sequences can usually be categorized into two different types: progressive and interlaced. With progressive video all the picture elements comprising a frame of video data are sampled at the same moment in time. With interlaced video, alternative lines of the video image are sampled at alternate moments in time; the resulting interlaced video frame is therefore made up of two “fields” each field being half the height of the video frame.
Examples of interlaced video sequences are TV signals and the output of DV camcorders. Examples of progressive video sequences are certain DVD's and computer generated video such as the output of the Windows® Media Video encoder. Additionally, some professional-level video cameras also generate progressive video.
Computer monitors and other like display devices are examples of a “progressive display system” and are therefore able to display progressive video without any additional processing. Interlaced video cannot be displayed on a computers monitor unless it has first been “de-interlaced”.
The current technique for de-interlacing video in a conventional personal computer (PC) requires the use of a “graphics overlay device” by a graphics processor. There are several restrictions and limitations to the use of the graphics overlay devices and as a consequence of this their usage will likely be deprecated in the future. For example, for most PCs there can only be one graphics overlay device. Additionally, most graphics overlay devices only provide a crude de-interlacing algorithm, such as, e.g., the BOB algorithm.
Consequently, for these reasons and others there is a need for improved methods and apparatuses for facilitating the de-interlacing of video.